The present invention relates to a confocal probe for obtaining a high-magnification tomogram of in vivo tissues in a human cavity.
Conventionally, when in vivo tissues are investigated at a thorough examination of a body, tissues at a targeted portion is collected using a cutting forceps or the like, and the collected tissues are investigated extracorporeally. Therefore, it takes relatively long time to obtain a diagnosis result, and an appropriate treatment of a patient cannot be taken immediately.
Recently, in order to accelerate the diagnosis procedure, confocal probe devices have been widely used. The confocal probe enables an operator to perform a non-invasive observation of a tomogram of in vivo tissues. The confocal probe device typically includes a micro-machined fine probe which is employed in confocal microscopes. The confocal probe is typically provided with a scanning mirror provided inside the probe to scan a laser beam on the target (i.e., human tissues) to capture a two-dimensional or three-dimensional image of the target.
As an example of such a confocal probe, a confocal microscope is disclosed in PCT Publication W099/44089, teachings of which are incorporated herein by reference. In the confocal microscope illustrated in the above publication, a region of interest is illuminated with a confocal spectrum extending in one direction, and the spectrum is scanned along one or two additional dimension. Then, a reflected confocal spectrum is detected to obtain a two-dimensional or three-dimensional image of the region of interest. As shown in FIG. 6, which schematically illustrates the conventional probe disclosed in the publication, a polychromatic beam emerged from an optical fiber is incident on a diffraction grating. The incident beam is dispersed by the grating, and focused by an objective lens onto the region of interest.
Since the confocal microscope described above employs the diffraction grating, relatively large amount of light may be lost when the multi-spectrum light rays are diffracted. Further, the dispersed light may not have even intensity distribution in the dispersed direction. Therefore, an image obtained by such a confocal microscope may be deteriorated due to uneven illumination of the region of interest.
The confocal microscope should be configured such that the light reflected by the region of interest should proceed along the optical path same as that used for illuminating the region of interest. In this regard, the light rays should be incident on the region of interest substantially perpendicularly (i.e., at the incident angle of 0°). Thus, according to the conventional confocal microscope as shown in FIG. 6, it is impossible to arrange the optical path of the light emerged from the objective lens and the optical path of the light incident on the diffraction grating to be parallel with each other. Therefore, the confocal microscope as a whole may be relatively large, or the confocal microscope may have a portion having a relatively large diameter, which prevents installation of the confocal microscope to a main body of a device. Further, a large size or diameter of the confocal microscope prevents a smooth operation thereof by an operator and/or causes pain to a patient.